The present invention relates to a rotor and a motor.
A rotor having the so-called Lundell-type structure using a permanent magnet field is one type of a rotor for a motor. Such a rotor includes two rotor cores and a field magnet. Each of the rotor cores includes a plurality of claw-shaped magnetic poles arranged in the circumferential direction. The rotor cores are combined with each other so that the field magnet is located between the two rotor cores. This results in the claw-shaped magnetic poles alternately functioning as different magnetic poles.
Japanese Laid-Open Patent Publication No. 2012-115085 describes a rotor. Auxiliary magnets, such as interpolar magnets magnetized in the circumferential direction, are arranged between claw-shaped magnetic poles in the circumferential direction to reduce flux leakage in the rotor.
In this rotor, however, the field magnet and the auxiliary magnets, which are affected by the ambient environment, may be demagnetized or damaged.
It is an object of the present invention to provide a rotor and a motor capable of protecting permanent magnets and preventing deterioration in the performance of the permanent magnets.
To achieve the above object, one aspect of the present invention is a rotor including a first rotor core, a second rotor core, a permanent magnet, and a resin layer. The first rotor core includes a substantially disk-shaped first core base and a plurality of first claw-shaped magnetic poles arranged at equal intervals on a peripheral portion of the first core base. Each of the first claw-shaped magnetic poles projects outward in the radial direction and extends in the axial direction. The second rotor core includes a substantially disk-shaped second core base and a plurality of second claw-shaped magnetic poles arranged at equal intervals on a peripheral portion of the second core base. Each of the second claw-shaped magnetic poles projects outward in the radial direction and extends in the axial direction, and the first rotor core and the second rotor core are combined with each other so that the first and second core bases are opposed to each other and the first and second claw-shaped magnetic poles are alternately arranged in the circumferential direction. The permanent magnet includes at least a main field magnet. The main field magnet is located between the first and second core bases in the axial direction and is magnetized in the axial direction, and the main field magnet causes the first claw-shaped magnetic poles to function as first magnetic poles and causes the second claw-shaped magnetic poles to function as second magnetic poles. The resin layer covers at least a portion of a surface of the permanent magnet.
A second aspect of the present invention is a rotor including a first rotor core, a second rotor core, a field magnet, and an auxiliary magnet. The first rotor core includes a first core base and a plurality of first claw-shaped magnetic poles arranged at equal intervals on a peripheral portion of the first core base. The first claw-shaped magnetic poles project outward in the radial direction and extend in the axial direction. The second rotor core includes a second core base and a plurality of second claw-shaped magnetic poles arranged at equal intervals on a peripheral portion of the second core base. The second claw-shaped magnetic poles project outward in the radial direction and extend in the axial direction, and the first rotor core and the second rotor core are combined with each other so that the first and second core bases are opposed to each other and the first and second claw-shaped magnetic poles are alternately arranged in the circumferential direction. The field magnet is located between the first and second core bases in the axial direction and magnetized in the axial direction. The field magnet causes the first claw-shaped magnetic poles to function as first magnetic poles and causes the second claw-shaped magnetic poles to function as second magnetic poles. The auxiliary magnet is formed by at least one of a back surface magnet and an interpolar magnet. The back surface magnet is located between the field magnet and a corresponding one of the first and second claw-shaped magnetic poles to limit flux leakage therebetween, and the interpolar magnet is located between adjacent ones of the first and second claw-shaped magnetic poles in the circumferential direction to limit flux leakage therebetween. At least one of the field magnet and the auxiliary magnet includes a non-abutment portion that partially blocks abutment between the field magnet and the auxiliary magnet.
A third aspect of the present invention is a rotor including a first rotor core, a second rotor core, and a field magnet. The first rotor core includes a substantially disk-shaped first core base and a plurality of first claw-shaped magnetic poles arranged at equal intervals on a peripheral portion of the first core base. Each of the first claw-shaped magnetic poles projects outward in the radial direction and extends in the axial direction. The second rotor core includes a substantially disk-shaped second core base and a plurality of second claw-shaped magnetic poles arranged at equal intervals on a peripheral portion of the second core base. Each of the second claw-shaped magnetic poles projects outward in the radial direction and extends in the axial direction, and the first rotor core and the second rotor core are combined with each other so that the first and second core bases are opposed to each other and the first and second claw-shaped magnetic poles are alternately arranged in the circumferential direction. The field magnet is located between the first and second core bases in the axial direction and magnetized in the axial direction so that the first claw-shaped magnetic poles function as first magnetic poles and the second claw-shaped magnetic poles function as second magnetic poles. The field magnet includes two side surfaces in the axial direction. At least one of the two side surfaces includes a dividing groove that is recessed in the axial direction and extends in the radial direction.